Hi - I'm in agreement with Eric that the key is the census entry for Catherine Fell age 16 born IOM, along with family names which appear to connect Jane to Isabella Stevenson.
See again: www.isle-of-man.com/cgi-bin/interests/genealogy/bulletin/index.pl?noframes;read=527080
Also -
www.isle-of-man.com/cgi-bin/interests/genealogy/bulletin/index.pl?noframes;read=527189

Have you been able to follow up Eric's suggestion to look at a copy of the original register to see if there's a transcription mistake for Jane's name?

If you print out the extracted entries for their children from the IGI it will help you find them quickly when looking at the films, but it is a good idea to also carefully check each entry between the dates Jane might have been baptised in case there is an entry for her (not on the IGI) which has been badly written, and mistranscribed. And also whether one of the other children's names was really Jane, but written badly.
I had a look at a couple of censuses because her age fluctuated so much in the ones you gave, and I read her age in 1851 as 40, not 48. These indicate a birth for her between 1810 and 1815.

The LDS film numbers for extracted entries are given under "Source Call No" at the bottom of the screen.
Their children bapt Braddan are on LDS film no: 0106708.
Their children bapt at Saint George, Douglas are on LDS film no.0106717
Their marriage on 12 Nov. 1791 Braddan is a submitted entry, but these often replace the parish register transcript, so you should look for this in Braddan on LDS film no. 106709.

Look in the phone book for the closest LDS Family History Centre to order the films to view, under "Church of Jesus Christ of Latter Day Saints". There is a small fee to order the film, and they would usually allow you to order the three at once.

Sue